For various reasons, it has been proven feasible to make exercise devices relatively compact so that they can be utilized indoors. Normally, physiological benefits of walking and running require considerable space which has been traditionally available only outdoors and on a limited basis by indoor tracks. Perhaps three decades ago, treadmills were developed, primarily for medical purposes, so that physiological phenomenon, such as heart rates, could be conveniently measured. Since that time, treadmills have also gained wide acceptance as exercise devices because they require little space, are easy to calibrate and take measurements for physiological purposes and because they may be used regardless of the weather.
The benefits of stair climbing for cardiovascular exercise has long been recognized. Athletes such as rowers and football players increase their strength and endurance by running up stadium stairs. Starting in the 1960's, the patent literature, as exemplified by U.S. Pat. No. 3,497,215 to Harrison et al., includes a number of exercise escalators or stair steppers, wherein treadmills are given a vertical component so that the user combines normal walking, or perhaps even jogging, with the task of overcoming additional gravitational forces.
These exercise escalators or stair step-type treadmill exercisers now include devices such as brakes in order to adjust the force required of the person by the exercise device and to provide various readouts of interest to the operator. Such devices are perhaps exemplified by U.S. Pat. No. 4,687,195 to Potts.
In U.S. Pat. No. 5,145,475 to Cares, the concept of exercising the arms and upper body simultaneously with exercising the legs as well as the heart and lungs is now of considerable interest. This in part results from a recognition of the physiological benefits of cross-country skiing which are duplicated for indoor exercising with devices such as the NORDITRACK.RTM.. However, the Nordatrak.RTM.-type machine does not add an additional gravitational component to the existing gravitational component which is overcome when walking or running horizontally.
While the prior art discloses stair stepping types of exercising devices, the prior art has yet to provide a device which can vary the amount of gravitational force which the exerciser must overcome in combination with exercising the upper body and torso as well as the lower body.